Berlin 2024 – scientific programme

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MA: Fachverband Magnetismus

MA 46: Poster II

MA 46.85: Poster

Thursday, March 21, 2024, 15:00–18:00, Poster C

Estimation of the conventional giant barocaloric effect in Ni₅₀Mn_34.8In_14.2B — •Sven Wiesekopsieker^1,2, Tapas Samanta¹, Chris Taake¹, Laila Bondzio¹, Andreas Hütten¹, and Luana Caron^1,2 — ¹Faculty of Physics, Bielefeld University, Bielefeld 33501, Germany — ²Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 12489, Germany

Heusler alloys such as NiMn(In, Ga, Sn)-based systems are of special interest because they display a magnetostructural transition of first-order, necessary for a large barocaloric effect (BCE)[1]. The off-stoichiometric Heusler alloy Ni₅₀Mn_34.8In_14.2B shows a martensitic phase transition from a low T, low moment martensitic phase with monoclinic structure to a high T, ferromagnetic austenite phase with cubic L21 structure. We have studied the BCE in this compound using a combination of magnetic measurements under hydrostatic pressure and differential scanning calorimetry at 1 atm. Application of a pressure up to 8.2 kbar shifts the transition from 305 K up to 327 K and decreases thermal hysteresis from ca. 6.5 to 4.5 K at µ₀ H = 7 T. This, combined with a large transition entropy change of |Δ S_tr| = 35 J/(kg K), results in a decent refrigeration capacity which, compared to similar systems such as Ni_58.3Mn_17.1Ga_24.6 with Δ T_hyst= 11 K and |Δ S_tr| = 16 J/(kg K) [2], or Ni_44.6Co_5.5Mn_35.5In_14.4 with Δ T_hyst= 19 K and |Δ S_tr| =16 J/(kg K) [1], represents a large improvement.
[1] X. J. He et al., J. Scri. Mater. 145, 58 (2018)
[2] X. J. He et al., J. Mater. Sci. 52, 2915 (2017)

Keywords: Barocaloric effect; Heusler alloy; Ni-Mn-In; martensitic phase transition; indirect method